In this section we are sliding the background at a different speed to the rest of the page.
As this text box is scrolling at the same speed as the page, and faster than the background, it creates this lovely parallax effect.
You can find all the HTML, CSS and the all important JavaScript files over at GitHub - so why don't you drop by for some hardcore forking action?
Backgrounds for this article were taken from the May/June 2011 Smashing Magazine Desktop backgrounds.